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Thread: ESE's works engine tuner

  1. #29176
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    8th February 2007 - 20:42
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    Ha ha, I already use what is called a Hyper Coating,a thermal barrier coating usually used for retaining heat in exhaust systems.
    See here :http://www.hpcoatings.co.nz/ExhaustH...erCoat_Extreme.
    I just happened to see the inside of a special race engine at TM that had a black " coating " of some sort.
    The legality could strictly be questioned, as a basic rule of the class is " no added material ",but the coating has never been questioned by tech.
    Let alone the clear thermal barrier coating in the combustion chamber, that you cant see when oil residue is burnt onto its surface.

    JanBros - the big problem with trying to replicate the STA and or bmep of the Aprilia is that this engine was R&D'd to death on both the dyno and the flow bench.
    The STA numbers nowhere near match,as the Blowdown Cd is hugely affected by the port exit geometry,and this works way better than the raw numbers generated by the simply calculated area.
    Then you have a plethora of tiny details ( such as PWM powerjet operation ) and unless you replicate all of this synergy,the numbers you are trying to simulate in your own project are stuff of daydreams.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  2. #29177
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    12th March 2010 - 16:56
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    emissions problem solved
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  3. #29178
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    14th December 2015 - 07:33
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    Aprilia RS250 and Aprilia RS50->125cc
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    Quote Originally Posted by Flettner View Post
    emissions problem solved
    are you going to make it a side bleed?

  4. #29179
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    12th March 2010 - 16:56
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    yes, off the mid section.
    And yes I will weld a knob over the point but first I might just paint it up like a missile for a while.
    Years ago I built a uniflow engine jet boat, ran four chambers. They were too long for the short boat so I ran mid section bleed off. On arrival to the boat ramp there was a police training school happening there. As I got out of the car I had several concerned officers confront me asking why I had four missiles pointing out the back of my boat. Took quite a while to convince them that they were in fact exhausts, as in connected to the engine.
    Had I known i was going to meet these officers I would have painted them up like missiles, you know with red and yellow tips. Those officers watched me for some time, I don't think they trusted me, dumbarses.
    here it is in it's earlier form with just Rotax muffler on it.
    Not held at full throttle until later in the video at 5,20. Crank case charged, four pistons, two combustion chambers. Two crankshaft banks. Home cast pistons, fires as a single.
    https://youtu.be/uiXsPkP9jvw
    https://youtu.be/BPr694nlUKE

    I did say years ago!

  5. #29180
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    16th February 2017 - 14:26
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    2002 Yamaha YZ250WR
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    Quote Originally Posted by DoldGuy View Post
    Nath88,

    Most late model MX 250’s have about 184/185 exhaust 118/120 Transfers. When you overbore, the roof angles will lower the port window (sometimes a lot). The “lip” you referred to, is it on the sides of the port windows (you want those) or on the roof/floor of the window? I have not had my hands on a stock late YZ Cylinder but know that some tuners stagger the transfers for a broader power curve.

    Enjoy your post & videos on the FI, keep sharing!
    Thanks for the info! I foolishly forgot to measure the roof angles, hopefully they don't change too much with the overbore, I'm going to aim for 189/190 on exhaust, 123 on rear transfer and 121 on main transfers. While retaining the standard roof angles/widths.

    I want to investigate staggering the aux exhaust ports above the main maybe 190 aux, 188 main. I'm sure the answer will lie somewhere in this forum.

    The lips are the whole way around the port, the cylinder has been replated before, so that may be a contributor. I'll get the guy to pay close attention there when he corrects the chamfer after plating.

  6. #29181
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    8th February 2007 - 20:42
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    Lifting the Aux is a big mistake.It was done years ago in a Kawasaki MX 125 but they alone were controlled by a PV.
    Even then it didnt work at all well.
    You need at least 4* duration stagger below the main Ex,or all the mid evaporates.
    Same with the transfers, why are you lifting the B above the main, this also kills the lower mid power.
    For a wider band width you need proper dropping stagger with the A port highest.
    When you overbore, the ducts with steeper angles,like the A and C will drop way more than the flatter B roof, so this needs to be corrected before plating, as does putting a proper chamfer
    into the top and bottom of the main Exhaust.
    Having a chrome lip all around the ports simply means the plater was a bloody lazy cheapskate.
    Instead of just guessing all these port numbers,there are plenty of STA or Angle area calculators available to keep the relative power capability in line.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  7. #29182
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    16th February 2017 - 14:26
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    Quote Originally Posted by wobbly View Post
    Lifting the Aux is a big mistake.It was done years ago in a Kawasaki MX 125 but they alone were controlled by a PV.
    Even then it didnt work at all well.
    You need at least 4* duration stagger below the main Ex,or all the mid evaporates.
    Same with the transfers, why are you lifting the B above the main, this also kills the lower mid power.
    For a wider band width you need proper dropping stagger with the A port highest.
    When you overbore, the ducts with steeper angles,like the A and C will drop way more than the flatter B roof, so this needs to be corrected before plating, as does putting a proper chamfer
    into the top and bottom of the main Exhaust.
    Having a chrome lip all around the ports simply means the plater was a bloody lazy cheapskate.
    Instead of just guessing all these port numbers,there are plenty of STA or Angle area calculators available to keep the relative power capability in line.
    My bad terminology has caused confusion. Stock is:
    Main Exhaust: 185°
    Aux Exhaust: 185°
    A port: 117°
    B port: 117°
    C port: 120°

    So 'conventional stagger' A higher than B & C gives greater bandwidth, and 'reverse stagger' B & C higher than A gives a higher peak, if all ports are level is that somewhere in between?
    So if I raise the main exhaust port to 189, I should leave the aux ports where they are at 185.

    I'll measure the ports and use a calculator to see where it's at. I'm going to look into the radiused exhaust edge also. Cheers for the advice, I have a lot to think about.

  8. #29183
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    8th February 2007 - 20:42
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    Proper conventional stagger has all 3 ports dropping, and as the boost is going to be very low with the overbore,this makes it easy to implement.
    Yes, lifting the main and leaving the Aux is a good move,but absolutely no need for an Exhaust timing radius,as that was done solely to re calibrate the effective Cd
    and balance the Blowdown flow to the transfer STA.
    You can achieve way more Blowdown than is needed with conventional means.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  9. #29184
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    18th March 2012 - 08:35
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    I simulated staggered ports against reverse stagger yesterday in MOTA.
    Almost no difference.
    Reverse stagger had a small advantage at torque peak, about 0.5hp

    It suprised me actually.

  10. #29185
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    28th August 2015 - 00:01
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    1975 Hodaka Wombat
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    The problem with one dimensional sims is that they don't actually simulate scavenging, only the flow and pressure pulses through the engine. EngMod2T, a much more accurate sim than MOTA, still only uses scavenging models to determine scavenging efficiency. The fine details of scavenging flow need computer flow simulations to investigate. An easier method is the dyno. Two stroke power is very sensitive to scavenging efficiency.

    Lohring Miller

  11. #29186
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    27th October 2013 - 08:53
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    wob have you ever grinded a small groove into the top portion of a lectron needle like the picture (that's not my actual needle but just a random internet pic for illustration) ? I think this should allow more fuel at throttle close position. Ive already had the needle taper grinded more but I suspect it wont be enough, although I haven't ran the engine yet because of the weather. and the steeper you grind the taper at the top, it grinds into the needle threads , which hold the needle into the slide. so I don't want to grind the taper much more because it is removing more and more threads. this is why im thinking of another method to supply more fuel. im thinking I can grind a very shallow groove to start with and try it. if it still runs away I can continue to grind it wider and deeper as needed
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  12. #29187
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    20th October 2015 - 01:39
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    Quote Originally Posted by SwePatrick View Post
    I quote my self if anybody want to hear the progress.
    First pull on dyno, very raw and just setup to start and be safe in 'break in'
    29.2hp to the wheel at 14300rpm on 98 octane pump fuel.
    It revs very freely was the first spontaneus reaction, they pulled it all the way to 17000rpm by mistake
    I´m sorry to say that i isn´t there where they dyno it, we just have contact through the phone as is.

    Very low barometerpressure today in Sundsvall, only 1002hPa
    Would you like to share more information about the engine ?
    I'm very interested about your project. Great power and a lot of revs !

  13. #29188
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    8th February 2007 - 20:42
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    Peewee, the groove idea has been used bu Lectron to get more flow at WOT,as the problem is that you get to a point where the needle isnt supported
    sufficiently around its OD.
    But there is no need to grind anywhere near the threads,that portion of the needle isnt in the hole in the body,so has no effect on the flow at all.
    You can step down the flat a heap, where the stock taper feathers out to nothing.
    I would fit the needle to a slide ,sit it at idle height,then measure up the hole from the bottom.
    Take the needle off the slide, set it at the same height, and mark where it intersects the hole at the top,that is where your groove or deeper taper needs to start.
    The other way to change the flow dramatically is to raise the fuel level in the bowl.
    Lectrons are very sensitive to the height in the bowl at and around idle/transition.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  14. #29189
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    27th October 2013 - 08:53
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    yes thats what i plan to do. just grind a groove at the upper section of the needle where it intersection the top of the tube at idle position. i figure this is easier than trying to accuratly grind down the taper.

  15. #29190
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    12th March 2010 - 16:56
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    Quote Originally Posted by Flettner View Post
    so what are we talking, twin scroll water pump, twin Radiators. One feeding the crankcase, cylinder, head and one feeding the exhaust stub only?
    nah, single scroll pump, running the 360 on E85 it should run cool enough anyway.
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